SOLUTION: John has 300 feet of lumber to frame a rectangular patio (the perimeter of a rectangle is 2 times length plus 2 times width). He wants to maximize the area of his patio (area of a

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: John has 300 feet of lumber to frame a rectangular patio (the perimeter of a rectangle is 2 times length plus 2 times width). He wants to maximize the area of his patio (area of a       Log On


   



Question 51780: John has 300 feet of lumber to frame a rectangular patio (the perimeter of a rectangle is 2 times length plus 2 times width). He wants to maximize the area of his patio (area of a rectangle is length times width). What should the dimensions of the patio be, and show how the maximum area of the patio is calculated from the algebraic equation.
Show clearly the algebraic steps which prove your dimensions are the maximum area which can be obtained. Use the vertex form to find the maximum area.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
2l + 2w = 300
l = (300 - 2w) / 2
l = 150 - w
A = w*l
A = w*(150 - w)
A+=+150w+-+w%5E2
Let's say w = 75 (square patio)
A+=+150%2A75+-+75%5E2
A+=+11250+-+5625
A+=+5625
What if w = 74?
A+=+150%2A74+-+74%5E2
A+=+11100+-+5476
A+=+5624
What if w = 76?
A+=+150%2A76+-+76%5E2
A+=+11400+-+5776
A+=+5624
So, if I go up a little from w = 75 or down
a little from w = 75, A goes down.
w = 75 and l = 75 gives the max area